The present disclosure is generally related to monitoring wellbore operations and, more particularly, to observing downhole tool operations through surface monitoring of vibrations.
The oil industry has been gathering various information about well drilling for many years. Of great interest in modern petroleum drilling and production operations is information relating to the drill string and downhole tool operation. Such information may include the location of the drill string within the borehole or the status of a particular wellbore operation as undertaken by a downhole tool extended into the wellbore on a drill string or another type of tubing or conveyance. For example, it is often desired to know whether a particular downhole tool has actuated properly or otherwise operated as expected.
There are currently various methods that may be used to obtain and verify such downhole information. For example, well operators are sometimes able to ascertain whether a downhole tool has properly completed a wellbore operation by knowing the approximate depth of the tubing as extended into the wellbore (taking into account stretch and other parameters) and monitoring weight differentials in the tubing as measured at the surface. If a sliding sleeve has been properly closed, for example, the weight of the tubing as measured at the surface will register an identifiable weight change indicating the completion of such a closure. Similar weight changes may be monitored and identified at the surface for other downhole tools and wellbore operations, such as snapping a collet through a restriction, setting a packer, engaging a restriction with the tubing, etc.
Such a method, however, is not always available to provide a positive indication that the downhole tool has properly actuated or completed a wellbore operation. Rather, unless costly and time-consuming well testing is undertaken, the well operator may only assume that the downhole tool has properly actuated or completed the wellbore operation as based on measured weight differentials. Further, this weight differential method becomes unreliable in wells that reach depths of 20,000 feet or more, where the weight differential felt at the surface is reasonably insignificant as compared to the weight of the entire tubing. Measuring weight differentials at the surface in deviated or horizontal wells can also be an unreliable means of determining downhole tool activation since a good portion of the tubing weight is assumed through contact with the wellbore wall. As a result, inaccurate measurements can be rendered in deep and/or deviated wells.